I've just got a new headtorch, to replace a Tikka XP2 that's got one of the clips holding the front and back halves of the body together broken.
(Zebralight H600Fw II, clicky image)
It's an 18650 powered light offering 6 brightness levels between 960 lumens (2 hours) and 0.06 lumens (4.5 months), as currently set. It's nice to have a light that can be used without wrecking your night vision (eg finding something in your saddlebag, or a keyhole).
Proper non-blue neutral colour (4400K), a nice smooth floody (non)beam. Versions with a regular torch beam for distance work available if that's your preference.
Maximum battery size is 69 mm long, 18.4 mm diameter. The 18 x 65 mm specfication size is for the as manufactured cell, and adding the overcharge/over-discharge protection than most consumer 18650s have adds 3-5 mm length, and a fraction on the diameter.
As an extra bonus, when selecting an 18650 to put in it, I found that you can now get them with a micro-USB port in the side, for charging without a charger. Plugged in to the PC at work, it took about 5 hours before the green LED came on, with the battery never getting more than mildly warm. I'd guess that it's taking 0.5A.
http://www.flashaholics.co.uk/products/ ... ttery.html